In its Stop Puppy Trafficking appeal, the USPCA has issued essential guidelines for new owners to guard against buying dogs which could be diseased and die within weeks.

The three-step plan urges potential owners not to buy pups in car parks from the back of a car or van, to always go to the breeder's premises and ask to see the puppy's real mother, and to check with the local council to confirm the breeder is licensed.

Currently there are 25 licensed breeders registered in Northern Ireland owning a total of just over 1,000 breeding bitches.

But the USPCA believes there are hundreds more ignoring the law or trading in litters bought in from a network of unregistered breeders and puppy farms.

Colleen Dowdall of the USPCA said while the Department of Agriculture, Environment and Rural Affairs and the 11 councils have responsibility for animal welfare and are driving forward robust breeder registration and inspection schemes, there is still a major issue with illegal cross-border trafficking.

"Designer puppies are changing hands for hundreds of pounds out of car boots in car parks and lay-bys all over the country with little or no thought to how they were bred, what vaccinations they have or the consequences of buying a sick dog that could cost thousands in vet bills if they survive the first few months of life," she said.

"Many of these puppies are being bred in the Republic of Ireland and are trafficked to Northern Ireland and on to Scotland."

Last year it emerged Northern Ireland topped the UK regional league of shame for unwanted dog numbers and consistently recorded the worst ratio of stray and abandoned dogs per head of population.

A survey showed Northern Ireland councils dealt with 5,170 stray dogs, compared to 102,363 in the whole of the UK. In Northern Ireland 409 of these dogs were put to sleep, 1,944 were reunited with owners and 1,411 were passed on to welfare organisations from councils.